Caps for writing implements such as pens, felt tip pens and similar that carry ducts and/or holes to allow the passage from the inside to the outside of their body are already on the market.
In case the cap is accidentally swollen and stops in the pharynx, the holes and/or ducts allow the victim of the accident to breathe sufficient air until the intervention of a physician who will remove the cap from the pharynx, or perform a tracheotomy if it is impossible to remove the cap easily and immediately. The caps found on the market at the moment offer some safety systems; however, the air passage openings are obtained only in the midway outer part of the cap or on the closed upper end.
In this way, the incoveniences are two: the total area for the air passage through the openings is insufficient for the desired safety; as the openings are only found at a single particular position along the length of the cap, the air passage would become insufficient to ensure the desired safety if the trachea sides should adhere to that position, or if some substances should accumulate and occlude the openings even only partially.